IR remotes are line of sight, if there's something directly between the remote and the receiver, it won't work. RF sends out a broadcast that can go around obstacles, but is prone to interference. Most electronics use IR remotes.
Any word yet on availability? A lot of sites are taking pre-orders now... some for under $200 too! (check froogle) I really don't know how they can sell it that cheap. To be honest, I'm not even sure if I trust 'em.
DigitalBuys seems like a safe bet though. They sell on eBay too and have a really clean (if not perfect) record.